Looks like I’ll have to stick with AnyDesk for a while longer. Too much trust in new technologies in Rustdesk. Software works in principle, but the UI needs rather new stuff. No joy with people having laptops with older NVIDIA GPUs, or even Mint 19.3 or 21.3 (yes, people still use that). Fluttr craps out even trying to only read the OpenGL version number!
The good part: If it works, Rustdesk works nicely. Even on Android (even though Google try to shun you from using it) and Windows. The screen transmission is slightly less performant than with Anydesk (they use their own codec), and heavily relies on hardware acceleration being available.
Also nice: Peaceful coexistence with Anydesk, meaning you can have both installed and they don’t interfere.
Another one to watch, Rustdesk is. Too bad they’re only “quasi Open Source” (you need proprietary “Pro” at an exorbitant pricing scheme for some lesser used features like the Adressbook). Apparently picked up that scheme from TeamViewer and AnyDesk. Lure them in, then restrict features and make them pay subscriptions… sigh.
Still worth a recommendation if you don’t have to support too many machines on which it doesn’t work.